The convention cycle begins with the Call to Convention. Usually issued about 18 months in advance, the Call is an invitation from the national party to the state and territory parties to convene to select a presidential nominee. It also sets out the number of delegates to be awarded to each, as well as the rules for the nomination process. The conventions are usually scheduled for four days of business, with the exception of the 1972 Republican and 2012 Democratic conventions, which were three days each. (The 2008 and 2012 Republican conventions were also three days each, but in each case was shortened from the scheduled four days due to weather issues).

There is no rule dictating the order of the conventions, but since 1956 the incumbent party has held its convention second. Between 1864 and 1952, the Democrats went second every year (except for 1888). In 1956, when RepublicanDwight D. Eisenhower was the incumbent, the Democrats went first, and the party out of power has gone first ever since. (Between 1936 and 1952, the Democrats were the incumbent party and went second, but it is unclear whether they went second because they held the White House or because they had always gone second.) Since 1952, all major party conventions have been held in the months of July, August or (for the first time in 2004), early September. (Election laws in some states would likely prevent conventions from moving into mid-September). Between the middle of the 20th century and 2004, the two major party conventions were primarily scheduled about one month apart, often with the Summer Olympics in between so they did not have to compete for viewers. In 1996, both were held in August to accommodate the Atlanta Olympics in July, the last Summer Olympics to date to be played in the U.S. In 2000, both conventions preceded the Sydney Olympics in late September.

In 2008 and 2012, the Democratic and Republican conventions were moved to back-to-back weeks following the conclusion of the Olympics. One reason for these late conventions had to do with campaign finance laws, which allow the candidates to spend an unlimited amount of money before the convention, but forbid fundraising after the convention, in order for the parties to receive federal campaign funds.[1] However, if Barack Obama's choice not to receive federal campaign funds for the 2008 general election is repeated in future elections, this reason for the late scheduling of conventions will no longer be valid. Another reason for the lateness of the conventions is due to the primary calendar, which ends in early June, and the political party's desire to turn the convention into a four-day tightly scripted political rally for their nominee, which just happens to have a roll call vote for President. This includes such logistics as where each delegation sits on the convention floor, the order of speeches, how the nominee wants to present him or herself, and allows time for any negotiations in regards to the running mate. Finally, the parties also did not want to schedule their conventions around the Olympics. One reason why the Democratic Party held its 2008 convention after the two-week-long Beijing Olympics was, according to them, to "maximize momentum for our Democratic ticket in the final months of the Presidential election".[2] But moving the conventions later into early September led to conflicts with the National Football League's season kickoff game, which opens the season on the first Thursday of September. However, the NFL accommodated the conventions and moved its games to an earlier start time in 2008,[3] and an earlier date in 2012.

In 2016, both the Republican and Democratic conventions moved to July, before the Rio de Janeiro Olympics in August. One reason why the Republican Party wanted a July convention was to help avoid a drawn-out primary battle similar to what happened in 2012 that left the party fractured heading into the general election. The Democrats then followed suit so they could provide a quicker response to the Republicans, rather than wait for more than two weeks until after the Olympics are over.[4]

Each party sets its own rules for the participation and format of the convention. Broadly speaking, each U.S. state and territory party is apportioned a select number of voting representatives, individually known as delegates and collectively as the delegation. Each party uses its own formula for determining the size of each delegation, factoring in such considerations as population, proportion of that state's Congressional representatives or state government officials who are members of the party, and the state's voting patterns in previous presidential elections. The selection of individual delegates and their alternates, too, is governed by the bylaws of each state party, or in some cases by state law.

The 2004 Democratic National Convention counted 4,353 delegates and 611 alternates. The 2004 Republican National Convention had 2,509 delegates and 2,344 alternates. But these individuals are dwarfed by other attendees who do not participate in the formal business of the convention. These include non-delegate party officials and activists, invited guests and companions, and international observers, not to mention numerous members of the news media, volunteers, protesters, and local business proprietors and promoters hoping to capitalize on the quadrennial event.

The convention is typically held in a major city selected by the national party organization 18–24 months before the election is to be held. As the two major conventions have grown into large, publicized affairs with significant economic impact, cities today compete vigorously to be awarded host responsibilities, citing their meeting venues, lodging facilities, and entertainment as well as offering economic incentives.

The location of early conventions was dictated by the difficulty of transporting delegates from far-flung parts of the country; early Democratic and Whig Conventions were frequently held in the central Eastern Seaboard port of Baltimore, Maryland. As the U.S. expanded westward and railroads connected cities, Midwestern cities such as Chicago, Illinois—which since 1860 has held 25 Republican and Democratic Conventions combined, more than any other urban center in the USA—became the favored hosts. In the present day, political symbolism affects the selection of the host city as much as economic or logistical ones do. A particular city might be selected to enhance the standing of a favorite son, or in an effort to curry favor with residents of that state. For example, in 2011, Obama campaign manager Jim Messina noted: “We put the Democratic National Convention in Charlotte, North Carolina in part because we believe so deeply in” a “New South map.”[5] Likewise, New York City was selected as the host of the 2004 Republican National Convention to evoke memories of George W. Bush's leadership in the September 11 attacks.

During the day, party activists hold meetings and rallies, and work on the platform. Voting and important convention-wide addresses usually take place in the evening hours.

In recent conventions, routine business such as examining the credentials of delegations, ratifying rules and procedures, election of convention officers, and adoption of the platform usually take up the business of the first two days of the convention. Balloting was usually held on the third day, with the nomination and acceptance made on the last day, but even some of these traditions have fallen away in 21st century conventions. The only constant is that the convention ends with the nominee's acceptance speech.

Each convention produces a statement of principles known as its platform, containing goals and proposals known as planks. Relatively little of a party platform is even proposed as public policy. Much of the language is generic, while other sections are narrowly written to appeal to factions or interest groups within the party. Unlike electoral manifestos in many European countries, the platform is not binding on either the party or the candidate.

Since the 1970s, voting has for the most part been perfunctory; the selection of the major parties' nominees have rarely been in doubt, so a single ballot has always been sufficient. Each delegation announces its vote tallies, usually accompanied with some boosterism of their state or territory. The delegation may pass, nominally to retally their delegates' preferences, but often to allow a different delegation to give the leading candidate the honor of casting the majority-making vote.

Before the presidential nomination season actually begins, there is often speculation about whether a single front runner would emerge. If there is no single candidate receiving a majority of delegates at the end of the primary season, a scenario called a brokered convention would result, where a candidate would be selected either at or near the convention, through political horse-trading and lesser candidates compelling their delegates to vote for one of the front runners. The best example was the 1924 Democratic Convention, which took 103 ballots. The situation is more likely to occur in the Democratic Party, because of its proportional representation system,[8] but such a scenario has been the subject of speculation with regard to most contested nominations of both parties without actually coming to pass in recent years.[9][10][11][12][13][14][15][16] It is a common scenario in fiction, most recently in an episode of The West Wing. The closest to a brokered convention in recent years was at the 1976 Republican National Convention, when neither Gerald Ford nor Ronald Reagan received enough votes in the primary to lock up the nomination.[17] Since then, candidates have received enough momentum to reach a majority through pledged and bound delegates before the date of the convention.

More recently, a customary practice has been for the losing candidates in the primary season to release their delegates and exhort them to vote for the winning nominee as a sign of party unity. Thus, the vote tallied on the floor is unanimous or nearly so. Some delegates may nevertheless choose to vote for their candidate. And in 2008 both happened: Hillary Clinton received over 1,000 votes before she herself moved to nominate Barack Obama by acclamation, officially making it a unanimous vote.

The voting method at the conventions is a "roll call of the states" – which include territories such as Washington D.C., American Samoa, Guam, Puerto Rico, the U. S. Virgin Islands, and a catch-all "delegates abroad" category. The states are called in alphabetical order (Alabama is first; Wyoming is last). The state's spokesperson (who generally begins his or her speech with glowing comments about the state's history, geography, and notable party elected officials) can either choose to announce its delegate count or pass. Once all states have either declared or passed, those states which passed are called upon again to announce their delegate count. (Generally, a decision is made beforehand that some states will pass in the first round, in order to allow a particular state – generally either the presidential or vice presidential nominee's home state – to be the one whose delegate count pushes the candidate "over the top", thus securing the nomination.)

Vice Presidential voting has been problematic since the beginning, as the delegates generally don't really want to deal with it, and it provides for mischief, as was the case in 1972's Democratic Convention where the vote was scattered between 50 "candidates" and 1976 Republican convention, where the vote was also scattered widely. In 1988, both parties decided to have the designated candidate nominated by "suspending the rules" and declaring him or her nominated by "acclamation." The last Vice Presidential roll call vote was at the 1984 Republican convention.

If, after the first round of voting, there is no candidate with a majority of votes, subsequent roll calls are held. In between, "back room deals" can be made between candidates, swapping delegates for positions in the administration or other favors, or candidates can release their delegates to vote for whoever they personally prefer. Roll calls continue until one candidate has a majority. The record is held by the 1924 Democratic National Convention where divisions within the party concerning Prohibition led to 102 ballots between Alfred E. Smith and William G. McAdoo before the relatively unknown John W. Davis was chosen as a compromise candidate on the 103rd ballot.

Minor figures in the party are given the opportunity to address the floor of the convention during the daytime, when only the small audiences of C-SPAN and other cable television outlets are watching. The evening's speeches - designed for broadcast to a large national audience—are reserved for major speeches by notable, respected public figures; the speakers at the 2004 Democratic convention included Ted Kennedy, a forty-year veteran of the United States Senate, and Jimmy Carter, a former DemocraticPresident, while at the Republican convention speakers included Governor Arnold Schwarzenegger of California and Governor George Pataki of New York, two of the largest states in the nation.

Uniquely, Miller, by then a Senator, would also be the keynote speaker at the 2004 Republican convention, despite still maintaining his Democratic registration.

The final day of the convention usually features the formal acceptance speeches from the nominees for President and Vice President. Despite recent controversy maintaining that recent conventions were scripted from beginning to end, and that very little news (if any) comes out of the convention, the acceptance speech has always been televised by the networks, because it receives the highest ratings of the convention. In addition, the halls of the convention are packed at this time, with many party loyalists sneaking in. Afterwards, balloons are usually dropped and the delegates celebrate the nomination.

Media images of the event—angry mobs facing down police—damaged the image of the Democratic Party, which appointed a commission headed by South Dakota Senator George McGovern to select a new, less controversial method of choosing nominees. The McGovern–Fraser Commission settled on the primary election, adopted by the Democratic National Committee in 1968. The Republicans adopted the primary as their preferred method in 1972. Henceforth, candidates would be given convention delegates based on their performance in primaries, and these delegates were bound to vote for their candidate.

With the rise of the direct primary, and in particular with states moving earlier and earlier in the primary calendar since the 1988 election, the nominee has often secured a commanding majority of delegates far in advance of the convention. As such, the convention has become little more than a coronation, a carefully staged campaign event designed to draw public attention and favor to the nominee, with particular attention to television coverage. For instance, speeches by noted and popular party figures are scheduled for the coveted prime time hours, when most people would be watching.

As the drama has left the conventions, and complaints grown that they were scripted and dull pep rallies, viewership—and television network advertising revenue—have fallen off. Midway through the 1996 Republican National Convention, Nightline host Ted Koppel told viewers he was going back home, saying:

There was a time when the national political conventions were news events of such complexity that they required the presence of thousands of journalists ... But not this year ... This convention is more of an infomercial than a news event.[19]

Thus in subsequent election years, the broadcast networks began increasingly limiting their coverage, arguing that those interested can watch the proceedings on a cable news network such as CNN, MSNBC, or the Fox News Channel. In 2004, the big three networks started devoting only three hours of live coverage to each political convention, although there were highlights of speeches during the networks' morning and evening newscasts.

However, many journalists still believe that the public should be exposed to political conventions. PBS, of note, continues to provide full prime-time coverage of the political conventions, although it breaks away from minor speakers and mundane business for analysis and discussion.[20]C-SPAN broadcasts both major conventions in their entirety, and the parties stream their conventions on the internet.

The presence of journalists at presidential nominating conventions have increased with the television networks. In 1976, the Democratic Convention consisted of 3,381 delegates and 11,500 reporters, broadcasters, editors and camera operators.[21] This is on par with the increase in the number of televisions in American’s homes. In 1960, 87 percent of people had a television, compared to 98 percent by 1976.[22] By the 1992 conventions, network coverage increased from three networks (NBC, ABC and CBS) to five networks (NBC, ABC, CBS, Fox and PBS).[23] At the 1996 Republican National Convention there were approximately seven journalists per one delegate, or about 15,000 journalists.[21]

The increase of the media at these conventions originally led to a growth in the public’s interest in elections. Voter turnout in the primaries increased from less than five million voters in 1948 to around thirteen million in 1952.[24] By broadcasting the conventions on the television, people were more connected to the suspense and the decisions being made, therefore making them more politically aware, and more educated voters. When scholars studied the 1976 conventions they determined that by watching nomination conventions, even viewers that were not previously very politically active developed a much stronger interest in the election process and the candidate.[25]

The two right-hand columns show nominations by notable conventions not shown elsewhere. Some of the nominees (e.g. the Whigs before 1860 and Theodore Roosevelt in 1912) received very large votes, while others who received less than 1% of the total national popular vote are listed to show historical continuity or transition. Many important candidates are not shown here because they were never endorsed by a national party convention (e.g. William Henry Harrison in 1836, George C. Wallace in 1968, John B. Anderson in 1980 and Ross Perot in 1992).

Note that there is no organizational continuity between the American Parties of 1856 and 1972, the Union Parties of 1860, 1864, 1888 and 1936, or the Progressive Parties of 1912-16, 1924 and 1948-52. .

Presidential winner in bold.

M "Middle of the Road" faction of the People's Party, who opposed fusing with the Democrats after 1896.

¶ Note that the years refer to the relevant presidential election and not necessarily to the date of a convention making a nomination for that election. Some nominating conventions meet in the year before an election.

The individual article about a Libertarian convention after 1980 or a Green Party convention after 1996 is linked to its respective city in the table below. Cities linked for Constitution and U.S. Taxpayers' Party conventions lead to individual sections of Constitution Party National Convention.